The air tightness of an aluminum alloy hub is an important index for assessing the performance of the aluminum alloy hub, and methods for detecting the air tightness of the aluminum alloy hub generally include a water based air-tightness detection method and a helium-based air-tightness detection method. The water-based air-tightness detection method is commonly used and has the principle that inner and outer sides of the hub are closed; an inner cavity of a wheel rim is inflated with compressed air under certain pressure; then, the hub is immersed into water; whether air bubbles escape is observed with human eyes; if the air bubbles escape continuously, the air tightness of the hub is indicated to be unqualified; and if no air bubble escapes, the air tightness of the hub can be determined to be qualified. The helium-based air-tightness detection method is to determine the air tightness of the hub by analyzing the quantity of helium molecules with a helium gas as a leakage indication gas and a helium mass spectrometer as a detection member. During the helium-based air-tightness detection, a hub is sealed in an enclosed cover at first; an inner cavity of the hub is firstly vacuumized; then helium gas is charged into an outer cavity of the hub and the enclosed cover; if the hub undergoes leakage, molecules of the helium gas tend to enter the inner cavity of the hub; the helium molecules entered will be extracted into the helium mass spectrometer through a vacuum pump; and the air tightness of the hub is obtained through analysis.
In order to detect the accuracy of the helium-based air tightness detection device, an air-tightness standard hub with very small leakage rate needs to be used as a standard, and the helium-based air-tightness detection device can be calibrated by mounting a standard discharge spout on the air-tightness standard hub. When the standard discharge spout is closed, the leakage rate detected by the helium-based air-tightness detection device tends to be very small, reaching 10−12 to 10−13 Pa*m3/s generally; and when the standard discharge spout is opened, the standard leakage rate of the discharge spout shall be detected by the helium-based air-tightness detection device, which is 10−6 Pa*m3/s generally. Therefore, not only the standard discharge spout but also an air-tightness standard hub needs to be used for calibrating the accuracy of the helium-based air-tightness detection device.
It is known for those of ordinary skill in the detection art that the air-tightness standard hub may be worn or damaged during long-term use, and this may lead to changes in the air-tightness of the air-tightness standard hub, which consequently may be not suitable as the air-tightness standard hub any more. Due to higher requirements for the air-tightness standard hub, the cost on manufacturing and selecting the air-tightness standard hub is higher, and it is impossible to select a large amount of air-tightness standard hubs for frequent replacement. Therefore, there is an urgent need of a detection device having simple structure, convenient operation and accurate detection for the air-tightness standard hub in the actual production.
In some situations, the air-tightness detection is expected to be performed on a small amount of highly required vehicle wheels. This is also in need of a vehicle wheel air-tightness detection device, which is convenient to operate and accurate in measurement.